fix(coding-agent): handle reftable footer branch detection (#2300)

* fix(coding-agent): handle reftable footer branch detection

- Fall back to git commands when HEAD contains refs/heads/.invalid
- Treat unresolved .invalid as detached instead of showing literal .invalid
- Watch reftable directory for branch change updates
- Resolve commonGitDir for worktree setups

fixes #2123

* fix(coding-agent): improve reftable branch detection and reduce false-positive rerenders

- Re-resolve branch on watcher events instead of invalidating cache;
  only notify listeners when the branch string actually changed
- Add regression tests: regular repo fast path (no spawnSync), nested
  cwd upward walk, unchanged-branch reftable churn suppression
This commit is contained in:
Aaron Soules
2026-03-17 10:33:33 -04:00
committed by GitHub
parent 688ff9f10c
commit 2d05e87281
2 changed files with 279 additions and 35 deletions

View File

@@ -1,11 +1,18 @@
import { spawnSync } from "child_process";
import { existsSync, type FSWatcher, readFileSync, statSync, watch } from "fs";
import { dirname, join, resolve } from "path";
type GitPaths = {
repoDir: string;
commonGitDir: string;
headPath: string;
};
/**
* Find the git HEAD path by walking up from cwd.
* Find git metadata paths by walking up from cwd.
* Handles both regular git repos (.git is a directory) and worktrees (.git is a file).
*/
function findGitHeadPath(): string | null {
function findGitPaths(): GitPaths | null {
let dir = process.cwd();
while (true) {
const gitPath = join(dir, ".git");
@@ -15,13 +22,19 @@ function findGitHeadPath(): string | null {
if (stat.isFile()) {
const content = readFileSync(gitPath, "utf8").trim();
if (content.startsWith("gitdir: ")) {
const gitDir = content.slice(8);
const headPath = resolve(dir, gitDir, "HEAD");
if (existsSync(headPath)) return headPath;
const gitDir = resolve(dir, content.slice(8).trim());
const headPath = join(gitDir, "HEAD");
if (!existsSync(headPath)) return null;
const commonDirPath = join(gitDir, "commondir");
const commonGitDir = existsSync(commonDirPath)
? resolve(gitDir, readFileSync(commonDirPath, "utf8").trim())
: gitDir;
return { repoDir: dir, commonGitDir, headPath };
}
} else if (stat.isDirectory()) {
const headPath = join(gitPath, "HEAD");
if (existsSync(headPath)) return headPath;
if (!existsSync(headPath)) return null;
return { repoDir: dir, commonGitDir: gitPath, headPath };
}
} catch {
return null;
@@ -33,6 +46,17 @@ function findGitHeadPath(): string | null {
}
}
/** Ask git for the current branch. Returns null on detached HEAD or if git is unavailable. */
function resolveBranchWithGit(repoDir: string): string | null {
const result = spawnSync("git", ["--no-optional-locks", "symbolic-ref", "--quiet", "--short", "HEAD"], {
cwd: repoDir,
encoding: "utf8",
stdio: ["ignore", "pipe", "ignore"],
});
const branch = result.status === 0 ? result.stdout.trim() : "";
return branch || null;
}
/**
* Provides git branch and extension statuses - data not otherwise accessible to extensions.
* Token stats, model info available via ctx.sessionManager and ctx.model.
@@ -40,28 +64,21 @@ function findGitHeadPath(): string | null {
export class FooterDataProvider {
private extensionStatuses = new Map<string, string>();
private cachedBranch: string | null | undefined = undefined;
private gitWatcher: FSWatcher | null = null;
private gitPaths: GitPaths | null | undefined = undefined;
private headWatcher: FSWatcher | null = null;
private reftableWatcher: FSWatcher | null = null;
private branchChangeCallbacks = new Set<() => void>();
private availableProviderCount = 0;
constructor() {
this.gitPaths = findGitPaths();
this.setupGitWatcher();
}
/** Current git branch, null if not in repo, "detached" if detached HEAD */
getGitBranch(): string | null {
if (this.cachedBranch !== undefined) return this.cachedBranch;
try {
const gitHeadPath = findGitHeadPath();
if (!gitHeadPath) {
this.cachedBranch = null;
return null;
}
const content = readFileSync(gitHeadPath, "utf8").trim();
this.cachedBranch = content.startsWith("ref: refs/heads/") ? content.slice(16) : "detached";
} catch {
this.cachedBranch = null;
if (this.cachedBranch === undefined) {
this.cachedBranch = this.resolveGitBranch();
}
return this.cachedBranch;
}
@@ -103,37 +120,73 @@ export class FooterDataProvider {
/** Internal: cleanup */
dispose(): void {
if (this.gitWatcher) {
this.gitWatcher.close();
this.gitWatcher = null;
if (this.headWatcher) {
this.headWatcher.close();
this.headWatcher = null;
}
if (this.reftableWatcher) {
this.reftableWatcher.close();
this.reftableWatcher = null;
}
this.branchChangeCallbacks.clear();
}
private setupGitWatcher(): void {
if (this.gitWatcher) {
this.gitWatcher.close();
this.gitWatcher = null;
}
private notifyBranchChange(): void {
for (const cb of this.branchChangeCallbacks) cb();
}
const gitHeadPath = findGitHeadPath();
if (!gitHeadPath) return;
private refreshGitBranch(): void {
const nextBranch = this.resolveGitBranch();
if (this.cachedBranch !== undefined && this.cachedBranch !== nextBranch) {
this.cachedBranch = nextBranch;
this.notifyBranchChange();
return;
}
this.cachedBranch = nextBranch;
}
private resolveGitBranch(): string | null {
try {
if (!this.gitPaths) return null;
const content = readFileSync(this.gitPaths.headPath, "utf8").trim();
if (content.startsWith("ref: refs/heads/")) {
const branch = content.slice(16);
return branch === ".invalid" ? (resolveBranchWithGit(this.gitPaths.repoDir) ?? "detached") : branch;
}
return "detached";
} catch {
return null;
}
}
private setupGitWatcher(): void {
if (!this.gitPaths) return;
// Watch the directory containing HEAD, not HEAD itself.
// Git uses atomic writes (write temp, rename over HEAD), which changes the inode.
// fs.watch on a file stops working after the inode changes.
const gitDir = dirname(gitHeadPath);
try {
this.gitWatcher = watch(gitDir, (_eventType, filename) => {
if (filename === "HEAD") {
this.cachedBranch = undefined;
for (const cb of this.branchChangeCallbacks) cb();
this.headWatcher = watch(dirname(this.gitPaths.headPath), (_eventType, filename) => {
if (!filename || filename.toString() === "HEAD") {
this.refreshGitBranch();
}
});
} catch {
// Silently fail if we can't watch
}
// In reftable repos, branch switches update files in the reftable directory
// instead of HEAD. Watch it separately so the footer picks up those changes.
const reftableDir = join(this.gitPaths.commonGitDir, "reftable");
if (existsSync(reftableDir)) {
try {
this.reftableWatcher = watch(reftableDir, () => {
this.refreshGitBranch();
});
} catch {
// Silently fail if we can't watch
}
}
}
}

View File

@@ -0,0 +1,191 @@
import { spawnSync } from "child_process";
import { existsSync, mkdirSync, mkdtempSync, rmSync, writeFileSync } from "fs";
import { tmpdir } from "os";
import { join } from "path";
import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
let resolvedBranch = "main";
vi.mock("child_process", () => ({
spawnSync: vi.fn((_command: string, args: readonly string[]) => {
if (args[1] === "symbolic-ref") {
return { status: resolvedBranch ? 0 : 1, stdout: resolvedBranch ? `${resolvedBranch}\n` : "", stderr: "" };
}
return { status: 1, stdout: "", stderr: "" };
}),
}));
import { FooterDataProvider } from "../src/core/footer-data-provider.js";
type WorktreeFixture = {
worktreeDir: string;
reftableDir: string;
};
function createPlainReftableRepo(tempDir: string): string {
const repoDir = join(tempDir, "repo");
mkdirSync(join(repoDir, ".git", "reftable"), { recursive: true });
writeFileSync(join(repoDir, ".git", "HEAD"), "ref: refs/heads/.invalid\n");
return repoDir;
}
function createPlainRepo(tempDir: string): string {
const repoDir = join(tempDir, "repo");
mkdirSync(join(repoDir, ".git"), { recursive: true });
writeFileSync(join(repoDir, ".git", "HEAD"), "ref: refs/heads/main\n");
return repoDir;
}
function createReftableWorktree(tempDir: string): WorktreeFixture {
const repoDir = join(tempDir, "repo");
const commonGitDir = join(repoDir, ".git");
const gitDir = join(commonGitDir, "worktrees", "src");
const worktreeDir = join(tempDir, "worktree");
const reftableDir = join(commonGitDir, "reftable");
mkdirSync(gitDir, { recursive: true });
mkdirSync(reftableDir, { recursive: true });
mkdirSync(worktreeDir, { recursive: true });
writeFileSync(join(worktreeDir, ".git"), `gitdir: ${gitDir}\n`);
writeFileSync(join(gitDir, "HEAD"), "ref: refs/heads/.invalid\n");
writeFileSync(join(gitDir, "commondir"), "../..\n");
writeFileSync(join(reftableDir, "tables.list"), "0\n");
return { worktreeDir, reftableDir };
}
async function waitFor(condition: () => boolean, timeoutMs = 2000): Promise<void> {
const startedAt = Date.now();
while (!condition()) {
if (Date.now() - startedAt > timeoutMs) {
throw new Error("Timed out waiting for condition");
}
await new Promise((resolve) => setTimeout(resolve, 10));
}
}
describe("FooterDataProvider reftable branch detection", () => {
let originalCwd: string;
let tempDir: string;
beforeEach(() => {
originalCwd = process.cwd();
tempDir = mkdtempSync(join(tmpdir(), "footer-data-provider-"));
resolvedBranch = "main";
vi.mocked(spawnSync).mockClear();
});
afterEach(() => {
process.chdir(originalCwd);
if (tempDir && existsSync(tempDir)) {
rmSync(tempDir, { recursive: true, force: true });
}
});
it("uses HEAD directly in a regular repo from a nested directory", () => {
const repoDir = createPlainRepo(tempDir);
const nestedDir = join(repoDir, "src", "nested");
mkdirSync(nestedDir, { recursive: true });
process.chdir(nestedDir);
const provider = new FooterDataProvider();
try {
expect(provider.getGitBranch()).toBe("main");
expect(vi.mocked(spawnSync)).not.toHaveBeenCalled();
} finally {
provider.dispose();
}
});
it("resolves the branch via git when HEAD is .invalid in a reftable repo", () => {
const repoDir = createPlainReftableRepo(tempDir);
process.chdir(repoDir);
const provider = new FooterDataProvider();
try {
expect(provider.getGitBranch()).toBe("main");
expect(vi.mocked(spawnSync)).toHaveBeenCalledWith(
"git",
["--no-optional-locks", "symbolic-ref", "--quiet", "--short", "HEAD"],
expect.objectContaining({
cwd: expect.stringMatching(/repo$/),
encoding: "utf8",
stdio: ["ignore", "pipe", "ignore"],
}),
);
} finally {
provider.dispose();
}
});
it("resolves the branch via git in a reftable-backed worktree", () => {
const { worktreeDir } = createReftableWorktree(tempDir);
process.chdir(worktreeDir);
const provider = new FooterDataProvider();
try {
expect(provider.getGitBranch()).toBe("main");
} finally {
provider.dispose();
}
});
it("treats an unresolved .invalid reftable HEAD as detached", () => {
const repoDir = createPlainReftableRepo(tempDir);
process.chdir(repoDir);
resolvedBranch = "";
const provider = new FooterDataProvider();
try {
expect(provider.getGitBranch()).toBe("detached");
} finally {
provider.dispose();
}
});
it("does not notify listeners when reftable updates keep the same branch", async () => {
const { worktreeDir, reftableDir } = createReftableWorktree(tempDir);
process.chdir(worktreeDir);
const provider = new FooterDataProvider();
try {
expect(provider.getGitBranch()).toBe("main");
vi.mocked(spawnSync).mockClear();
const onBranchChange = vi.fn();
provider.onBranchChange(onBranchChange);
writeFileSync(join(reftableDir, "tables.list"), "1\n");
await waitFor(() => vi.mocked(spawnSync).mock.calls.length > 0);
expect(provider.getGitBranch()).toBe("main");
expect(onBranchChange).not.toHaveBeenCalled();
} finally {
provider.dispose();
}
});
it("updates the cached branch when the reftable directory changes", async () => {
const { worktreeDir, reftableDir } = createReftableWorktree(tempDir);
process.chdir(worktreeDir);
const provider = new FooterDataProvider();
try {
expect(provider.getGitBranch()).toBe("main");
resolvedBranch = "foo";
await new Promise<void>((resolve, reject) => {
const timeout = setTimeout(() => reject(new Error("Timed out waiting for branch change")), 2000);
provider.onBranchChange(() => {
clearTimeout(timeout);
resolve();
});
writeFileSync(join(reftableDir, "tables.list"), "1\n");
});
expect(provider.getGitBranch()).toBe("foo");
} finally {
provider.dispose();
}
});
});